parse

Parses HTTP Request for the qualifier and argument of a command.
Each servlet path segment, except the first (which is the command name itself), is a qualifier.
Each qualifier can be either a key or a key-value pair separated by a = sign.
Each request parameter key-value pair is an argument. A concrete command may specify mandatory
arguments (e.g. type must be mandatory argument for find command,
or q for query. The mandatory arguments, if any, are not captured
in the argument list.
The qualifiers and arguments are immutable after parse.